The classic SP0256-AL2 voice chip has appeared several times on these pages. If you have not seen the actual part before, you have almost certainly heard the resulting audio output.The latest Python library from prolific reverse computing enthusiasts [Nick Bild] Brought it The joy of the old chip to the Raspberry Pi platform, There is an additional trick; support for the Lord AY-3-8910 Sounder as well as.
SP0256-AL2 chip use Abnormal sound systemAllophones are a bit like small pieces of speech audio. When reproduced sequentially, they will produce intelligible phonemes, which form the basis of speech.The chip needs an external device to feed allophones to it at a normal rate. This is his job Gi-Pi library.
This speech synthesis technology is based on Linear predictive coding, Used to realize the human vocal tract model.This is the same as the encoding method used in the first generation of GSM digital mobile phones. Full priceBoth the LPC encoder and the LPC decoder exist on the mobile phone. The LPC encoder takes the audio from the user, breaks it down into tiny components of speech, and then simply sends the code representing the audio block instead of the actual audio. Obviously, more parameters are also sent to adjust the receiving end model. Therefore, the actual decoder is not completely different from what AY-3-8910 and related devices do, unless the user must create a list of audio blocks in advance and feed the chip at the required rate.
In terms of hardware, [Nick] His breadboard construction is not documented, but the SP0256-AL2 is fairly easy to drive. This is just a matter of converting the Pi’s 3.3V logic level to the chip’s 5V domain, and then using several parallel GPIOs to perform bit shocks on it. The PCM audio output is then low-pass filtered and fed into the audio mixer and power amplifier.
The AY-3-8910 can be processed similarly, except that it contains its own DAC module, so the output is already analog, you can simply feed the analog output directly into the mixer shared with the above.
We have introduced the AY-3-8910 sound chip before. Through this simple technique, the Arduino has been turned into a MIDI device. In the previously linked article, check out the sweet version of Mozart’s Queen of the Night aria from Mozart’s opera “The Magic Flute.”
The video after the break provides a (a bit short) demonstration of the resultant voice audio you can expect, as if you didn’t know it yet.